Sealed device for transmitting a rotational movement inside a chamber

Abstract

The application relates to a sealed device for transmitting a rotational movement inside a chamber from a drive shaft to a driven shaft, said drive shaft including at least one input section extending through a wall of the chamber and supported by two bearings, one of which is located inside the sealed casing very close to the output section, and intended to co-operate with a rotational drive means, and an output section engaged with the driven shaft and inclined by an angle a in relation to the input section. The device includes a sealed casing surrounding the portion of drive shaft located in the chamber. The sealed casing includes at least: a bellows portion conferring flexibility on the casing at the intersection between the axis of the input section and the axis of the output section of the drive shaft; and a rigid sleeve extending alongside the bellows portion in the direction of the end of the output section of the drive shaft. The application also relates to a method for producing a sealed transmission device.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a National Phase Entry of International Application No. PCT / FR2008 / 000182, filed on Feb. 13, 2008 which claims priority to French Patent Application No. 0753340, filed on Feb. 19, 2007, both of which are incorporated by reference herein.BACKGROUND AND SUMMARY[0002]The invention more particularly relates to a device making it possible to transmit the rotational movement to a pump shaft.[0003]In the prior art, sealed devices for transmitting a rotational movement inside a chamber are known. Such devices are more particularly disclosed in the French application for a patent FR 2 746 452 in the name of the applicant.[0004]The device described in the present document includes a drive shaft including an input section extending through a wall of the flow space of a pump and cooperating with a rotational driving means, and a section inclined in relation to the input section, the end of which is engaged with a driven shaft so a...

AI Technical Summary

Benefits of technology

[0004]The device described in the present document includes a drive shaft including an input section extending through a wall of the flow space of a pump and cooperating with a rotational driving means, and a section inclined in relation to the input section, the end of which is engaged with a driven shaft so as to transmit the rotational movement. In order to provide the sealing between the inside and the outside of the flow space, the portion of the drive shaft positioned in the flow space is surrounded with a non rotating sealed sleeve including two metallic bellows. The bellows are mounted to slide on the inclined section so as to provide a sufficient service life.

[0013]Thus, according to the invention, the sealed casing is stable since the portion of the bellows uses a restrictive number of juxtaposed annular elements. In addition, the excentration of the end of the inclined portion can be increased proportionally to the length of the rigid sleeve since this portion of the casing does not affect the rigidity of the casing. Thus, the effort required for the rotation of the driven shaft is reduced through the increase of the lever arm.

[0018]Advantageously, the drive shaft is mounted to rotate through a bearing mounted on a support extending inside said chamber. Thus, the bearing of the drive shaft is close to the point of transmission of the torque, which makes it possible to reduce the efforts applied on said bearing. Advantageously, the output section of the drive shaft is fixed to the input section through a supporting flange. Thus, the length of the input section is increased and the supporting bearing of the drive shaft can be positioned closer to the point of transmission of the torque.

Problems solved by technology

However, this type of device has disadvantages.

As a matter of fact, the maximum excentration of the end of the section inclined in relation to the output section is limited since the exceeding of such maximum excentration leads to the buckling of the bellows.

Now, the increase of the length of the bellows through the addition of several plies reduces the rigidity of the bellows and even makes it unstable in its movements.

Thus, because of this impossibility to increase the excentration under the threat of causing the buckling of the bellows, the effort required for driving into rotation the driven shaft is relatively high.

In addition, in the devices of the prior art, the bellows casing undergo deformations resulting from the difference in pressure between the inside of the casing and the chamber.

The consequence of such deformations is an increase in the constraints in some plies of the bellows which result in a reduction in the service life of said bellows.

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